Ammunition case neck sizing die

Abstract

A cylindrical mandrel is inserted through the neck of an ammunition case coaxially with the body of the case after which a collet is driven axially onto the neck to form the inside diameter of the neck to the outside diameter of the mandrel without changing the diameter of the case body. In another embodiment an annular bushing of elastomeric material is confined in a space around the neck and the bushing is compressed axially to cause it to bulge radially inwardly so as to apply a force for forming the neck to the mandrel.

I claim: 
     
       1. A die for sizing an ammunition case comprising a body, a neck at one end of the body for receiving a bullet and a head at the opposite end of the body in which there is a primer pocket and a central flash hole connecting the pocket to the interior of the body, said die comprising: a cylndrical element having a standard external thread for screwing into the standard thread of a reloading press and having an axial bore for receiving coaxially said case whose neck is to be sized and aligned concentric to said case body and head,   a cylindrical mandrel having an outside diameter substantially equal to the desired inside diameter of said neck, said mandrel being arranged for extending axially through said neck when said case is in said bore, said mandrel having a reduced diameter cylindrical tip extending axially for registering in the primer flash hole in said case when said mandrel extends through said neck and said body of the case,   radially inwardly flexing squeezing means in said bore of said cylindrical element arranged to surround said neck and responsive to an applied axial driving force causing relative axial movement between said case and said cylindrical element by squeezing only said neck of the case radially inwardly onto said mandrel to substantially conform the inside size of said neck to the size of said mandrel, and,   a pin on an end of the mandrel for being in said flash hole when said neck is being squeezed so said neck and case body are compelled to become concentric.   
     
     
       2. A die for sizing an ammunition case comprising a body, a neck at one end of the body for receiving a bullet and a head at the opposite end of the body in which there is a primer pocket and a central flash hole connecting the pocket to the interior of the body, said die comprising: a cylindrical element having a standard external thread for screwing into a standard thread of a reloading press and having an axial bore for receiving said case coaxially whose neck is to be sized and aligned concentric to said case body and head,   a cylindrical mandrel having an outside diameter substantially equal to the desired inside diameter of said neck, said mandrel being arranged for extending through said neck coaxially to said bore,   collet means comprised of a tubular body and a plurality of fingers formed on said tubular body for extending axially in said bore for flexing radially inwardly and outwardly, said fingers being arranged in a circle with space between said fingers so that a case can be inserted within said circle, said fingers being externally tapered at corresponding ends and being disposed circumjacent said neck of the case in said cylindrical element,   a member located in said bore of said cylindrical element and having an internally tapered hole coaxial with said bore in which hole said externally tapered finger ends register such that when an axial force is applied to said fingers said tapered ends wedge in said tapered hole to cause radial inward deflection of said fingers for squeezing the neck of said case on said mandrel without squeezing the body of the case, said mandrel having a reduced diameter axially extending tip for registering in the primer flash hole in said case when said mandrel extends through the neck and said body of the case to force said neck and body into being aligned and concentric when said neck is squeezed.   
     
     
       3. The device according to claim 2 wherein a free space remains between said fingers and the body of said case when said fingers squeeze send neck so the size of said case body is not attached. 
     
     
       4. A die for sizing the neck of an ammunition case comprising a body, an neck at one end of said body for receiving a bullet and a head at the opposite end of the body in which there is a primer pocket having a central flash hole connecting the pocket to the interior of the body, said die comprising: a cylindrical element having a standard external thread for scrwing into a standard thread of a reloading press and having a bore that is closed at one end,   a cylindrical mandrel fixed coaxially in said bore and extending away from said closed end toward the other end of the bore, said mandrel having an outside diameter substantially equal to the desired inside diameter of the neck and having a tip for extending into said central flash hole,   a member in said bore having a tapered counterbore diverging away from said closed end toward said other end,   collet means in said bore comprised of a tubular body having a portion extending out of said other end of the bore and an axially opposite portion having radial slots defining a plurality of radially inwardly deflectable fingers projecting axially from said tubular body for admitting the neck and body of said ammunition case between them, the ends of said fingers being tapered externally and complementarily to said tapered counterbore and extending toward said counterbore, said neck being between said ends of the fingers and said mandrel when a case is inserted in said cylindrical element,   applying an axial force on said portion of said tubular body of the collet means that extends from said cylindrical element when said case is pressed on said mandrel with said neck disposed between said ends of said fingers causing said tapered ends of the fingers to wedge into said tapered counterbore and be squeezed radially inwardly against said neck so as to conform the size of the inside of said neck with the size of said mandrel, and at the same time forcing said neck to be concentric over its entire length to said flash hole and said case body, said fingers being shaped such that only said ends thereof contact said neck of the case for a free space to remain between said fingers and case body when said neck is being squeezed so the size of said case body is not altered.   
     
     
       5. A die for sizing the neck of an ammunition case comprising a body and a neck for receiving a bullet, said die including: a tubular element having an external thread and an axial bore that is closed at one end,   a cylindrical mandrel arranged coaxially in said bore and extending away from said closed end toward the other end of said bore,   generally cylindrical sleeve means arranged coaxially in said bore with a portion of said sleeve means extending outwardly of said other end of the bore,   a bushing comprised of elastomeric material disposed in said bore concentrically to said mandrel and to said bore and proximate to said closed end, said bushing having a central hole whose diameter is sufficiently larger than the diameter of said mandrel to permit said neck of the case to enter between said mandrel and said bushing when said bushing is uncompressed and said case is pushed axially into said tubular element, applying an axial force on said outwardly extending portion of said sleeve means causing axial compression and radial inward expansion of said bushing to force said neck to acquire an inside diameter substantially equal to the outside diameter of said mandrel.   
     
     
       6. The device according to claim 5 wherein said mandrel has a reduced diameter tip at an end remote from the closed end of said bore for entering the centrally located primer flash hole in said case to maintain the body and neck of said case coaxial with said mandrel. 
     
     
       7. The device according to any one of claims 5 or 6 wherein a free space exists between the body of the case and said sleeve so said body size is not altered when said device is occupied by said case.